The Medicare National Correct Coding Initiative (NCCI) published Procedure to Procedure edits
that seek to prevent unbundling of services and overpayment. The requirements state that if one code defines a subset of work of another code, the codes should not be reported separately, which would be considered double billing. The notice states that modifier -59 defines a “Distinct Procedural Service” which represents a service that is separate and distinct from another service with which it would usually be considered to be bundled.

The document states that modifier -59 is often misused, and outlines the following uses (and
misuses) of modifier -59:

• Infrequently (and usually correctly) used to identify a separate encounter;

• Less commonly (and less correctly) used to define a separate anatomic site; and

• More commonly (and frequently incorrectly) used to define a distinct service.
In CR8863, CMS establishes the following new modifiers to be used as a subset of the -59
modifier:

• XE Separate Encounter, A Service That Is Distinct Because It Occurred During A Separate
Encounter

• XS Separate Structure, A Service That Is Distinct Because It Was Performed On A Separate
Organ/Structure,

• XP Separate Practitioner, A Service That Is Distinct Because It Was Performed By A
Different Practitioner, and

• XU Unusual Non-Overlapping Service, The Use Of A Service That Is Distinct Because It
Does Not Overlap Usual Components Of The Main Service

CMS will continue to recognize the -59 modifier, but notes that Current Procedural Terminology
(CPT) instructions state that the -59 modifier should not be used when a more descriptive
modifier is available. While CMS will continue to recognize the -59 modifier in many instances,
it may selectively require a more specific - X{EPSU} modifier for billing certain codes at high
risk for incorrect billing